JPH086039B2 - Organopolysiloxane composition and gel cured product thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to an addition reaction-type organopolysiloxane composition having a high poisoning resistance to solder flux and a gel cured product thereof.

(Prior Art) Conventionally, an addition reaction between an organopolysiloxane having a vinyl group bonded to a silicon atom and an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom in the presence of a platinum-based catalyst has been used. Various techniques for obtaining a gel-like elastic body (hereinafter, referred to as silicone gel) by curing by curing are known (Japanese Patent Publication Nos. 55-38992, 55-41705, 59-35932, JP 56-1
No. 43241, No. 62-39658, No. 63-35655,
63-33475, etc.).

The addition-reaction type silicone composition from which such a silicone gel can be obtained is used in many applications such as potting, coating, encapsulation and the like.

(Problems to be solved by the invention) However, recent developments in electric and electronic parts, miniaturization,
With the compounding of materials, problems that have not been considered in the past have arisen. For example, when the above-mentioned addition reaction type composition is used as a material for protecting ICs and insulating materials, solder flux remaining on the IC substrate causes inconveniences such as curing inhibition, interface uncuring, and hardness reduction. Particularly in the case of low hardness potting materials and coating materials, such inconveniences occur remarkably, which is a serious problem.

Accordingly, the object of the present invention is to provide an addition reaction type organopolysiloxane composition capable of effectively achieving the intended purpose as a protective material for protecting ICs, wirings, etc., and an insulating material without impairing the curing characteristics due to solder flux and the like. It is to provide the gel cured product.

(Means for Solving the Problems) The present invention achieves the above object by using an organopolysiloxane having a siloxane unit having an aliphatic unsaturated group at a fixed ratio at a molecular end as a base polymer. It was successful.

According to the present invention, when (A) an aliphatic unsaturated group is represented by R ¹ and a monovalent unsubstituted or substituted hydrocarbon group containing no aliphatic unsaturated group is represented by R ² , 5 30 mol% consists of _0.5 units of (R ¹ ) ₃ SiO and 95-70 mol% of the molecular ends are R ¹ (R ² ) ₂ SiO
_An organopolysiloxane consisting of at least one unit selected from the group consisting of _0.5 units, (R ¹ ) ₂ R ² SiO _0.5 units and (R ² ) ₃ SiO _0.5 units, (B) on average in one molecule The organohydrogenpolysiloxane having two or more SiH groups, (C) an addition reaction catalyst, wherein the organohydrogenpolysiloxane (B) has a SiH group whose organohydrogenpolysiloxane (A 0.5) per 1 mol of the aliphatic unsaturated group contained in
Organopolysiloxane compositions are provided that are contained in a proportion such that they are up to 3 moles.

Further, according to the present invention, a gel cured product obtained by curing the above composition is provided.

(A) Organopolysiloxane The above-mentioned organopolysiloxane (A) has an average composition of the following formula [I]: In the formula, R ¹ is the above-mentioned aliphatic unsaturated group, R ² is the above-mentioned monovalent unsubstituted or substituted hydrocarbon group containing no aliphatic unsaturated group, and a is 0 <a. The number <3 and b are represented by the number 0 <b <3 (where 0 <a + b <4).

In the present invention, in the organopolysiloxane having such an average composition, 5 to 30 mol% of the molecular end of the organopolysiloxane is used.
Is composed of (R ¹ ) ₃ SiO _0.5 unit and has 95 to 70 at the molecular end.
Mol% is R ¹ (R ² ) ₂ SiO _0.5 unit, (R ¹ ) ₂ R ² SiO _0.5 unit and
It is composed of at least one unit selected from the group consisting of (R ² ) ₃ SiO _0.5 units, and those end-blocked by these units are used.

In general, the inhibition of curing by solder flux is due to the fact that the organohydrogenpolysiloxane that contributes to the crosslinking reaction
It is considered that SiH groups are generated because they react with the carboxyl groups in abietic acid, which is the main component of solder flux. Thus, according to the present invention, the presence of an aliphatic unsaturated group, which is a crosslinkable functional group possessed by the organopolysiloxane used as the base polymer, at the molecular end increases the curing rate, and as a result,
The reaction between the SiH group and abietic acid was effectively suppressed, and the inhibition of hardening by solder flux was successfully avoided. In particular, the (R ¹ ) ₃ SiO _0.5 unit present at the terminal of the molecule is the most important factor for improving the flux resistance of the composition of the present invention, and if this unit is less than 5 mol%, it will depend on the solder flux. Curing inhibition occurs, and if it exceeds 30 mol%, it is disadvantageous in that the resulting gel cured product becomes too hard to function as a gel, and the curing inhibition by solder flux is prevented. In addition, another unit at the end of the molecule, R ¹ (R ² ) ₂ S
The iO _0.5 unit, the (R ¹ ) ₂ R ² SiO _0.5 unit, and the (R ² ) ₃ SiO _0.5 unit adjust the softness of the silicone gel after curing.

Examples of the aliphatic unsaturated group R ¹ include a vinyl group,
An alkenyl group having 2 to 8 carbon atoms such as an allyl group, an isopropenyl group, a butenyl group and a hexenyl group can be exemplified, and a vinyl group is most preferable. These aliphatic unsaturated groups R ¹ may be bonded to a silicon atom in the middle of the molecular chain, as long as the existing ratio of the molecular ends is within the above range.

Suitable examples of the monovalent unsubstituted or substituted hydrocarbon group R ² containing no aliphatic unsaturated group include, for example, a group having 1 to 20 carbon atoms, and preferably a group having 1 to 10 carbon atoms. Alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cyclobutyl group Groups; aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group; aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group; and some or all of the hydrogen atoms of these hydrocarbon groups are chlorine, Groups substituted with halogen atoms such as fluorine and bromine, cyano groups, etc., such as chloromethyl group, trifluoropropyl group,
Halogenated hydrocarbon groups such as chlorophenyl group, dibromophenyl group, tetrachlorophenyl group, difluorophenyl group, β-cyanoethyl group, γ-cyanopropyl group,
Examples thereof include cyanoalkyl groups such as β-cyanopropyl group. In the present invention, the group R ² is most preferably a methyl group because it is easy to synthesize and the resulting gel cured product has good heat resistance and physical properties.

The organopolysiloxane of component (A) used in the present invention may be linear or branched, or may be in the form of a mixture thereof. In order to form a gel cured product which is required to have cold resistance, a branched product is suitable.

Further, in order to use the composition of the present invention for applications such as casting, potting, coating, impregnation, and adhesion, it is necessary that the composition itself has appropriate fluidity, and even before curing. It must have suitable physical properties. From this point of view, the viscosity of the above organopolysiloxane (A) at 25 ° C. is 50 to 100,000c.
It is preferably in the range of P. Further, in the average composition formula [I], a and b are 0 <a <3 and 0 <b.
It is necessary to satisfy <3 and 0 <a + b <4, and the values of a and b are set so as to have the most suitable viscosity according to the application within the viscosity range.

The above-mentioned organopolysiloxane can be produced by a method known per se.

(B) Organohydrogenpolysiloxane The organohydrogenpolysiloxane (B) used in the present invention has an average of 2 or more units in one molecule.
It has a SiH group (that is, a hydrogen atom bonded to a silicon atom), and the SiH group and the aliphatic unsaturated group of the organopolysiloxane (A) undergo an addition reaction to form a gel cured product. is there. That is, the organohydrogenpolysiloxane (B) acts as a crosslinking agent. Such SiH groups may be present either at the terminal of the molecule or in the middle of the molecule.

Such an organohydrogenpolysiloxane (B)
Is, for example, the following average composition formula [II], In the formula, c is a number of 0 <c <3, d is a number of 0 <d ≦ 2, (where 1 ≦ c + d ≦ 3) R ³ is an aliphatic unsaturated group as in the above R ^2. It is a substituted or unsubstituted hydrocarbon group which is not included and is represented by. In the average composition formula [II], specific examples of the hydrocarbon group R ³ are the same as those exemplified for the hydrocarbon group R ² in the average composition formula [I] described above.

In this organohydrogenpolysiloxane, the siloxane skeleton may be linear, cyclic, branched or resinous, but if it is used in applications requiring cold resistance, it may be branched. Is preferred. Further, when a certain strength is required, it is preferable that the resin is soluble in a nonpolar solvent. Furthermore, the viscosity at 25 ° C is not particularly limited, but it is 10 to 1000 in terms of easiness of synthesis and workability.
It is preferably in the range of cP.

In the present invention, the blending amount of the organohydrogenpolysiloxane (B) is such that the SiH group is 0.5 to 3 mol, preferably 0.6 mol, per 1 mol of the aliphatic unsaturated group contained in the organopolysiloxane (A). The amount is about 1 mol. When the SiH group, that is, the amount of hydrogen atoms bonded to silicon atoms is less than the above range, the aliphatic unsaturated group remains in the gel cured product, the heat resistance is lowered, and the amount is more than the above range. If it is present, the heat resistance is lowered and there is a risk of foaming during curing.

(C) Addition Reaction Catalyst The addition reaction catalyst used in the present invention comprises an aliphatic unsaturated group (A) and a hydrosilyl group (SiH) (B).
Any catalyst that promotes an addition reaction with chloroplatinic acid, alcohol-modified chloroplatinic acid, a coordination compound of chloroplatinic acid with an olefin or vinylsiloxane or an acetylene compound, tetrakis (triphenylphosphine). ) Palladium, chlorotris (triphenylphosphine) rhodium and the like are used, but platinum-based ones are particularly preferable.

Such a catalyst is usually added in a proportion of 0.1 to 1000 ppm with respect to the total amount of the components (A) and (B).

Other compounding agents In the organopolysiloxane composition of the present invention,
In addition to the components (A) to (C) described above, various compounding agents known per se can be added.

For example, fumed silica, silica aerosil, precipitated silica, ground silica, diatomaceous earth, iron oxide, alumina,
The hardness of the gel cured product obtained from the composition of the present invention by adding an inorganic filler such as zinc oxide, titanium oxide, calcium carbonate, magnesium carbonate, zinc carbonate or carbon black,
Mechanical strength and the like can be adjusted. Of course, hollow inorganic fillers, hollow organic fillers, organosilicone resins, rubbery spherical fillers, etc. can also be added. In addition, polymethylvinylsiloxane cyclic compound, acetylene compound,
It is also possible to control the curing reaction by adding a reaction control agent such as an organic phosphorus compound. The amount of these compounding agents used is arbitrary as long as the properties of the gel cured product to be obtained are not impaired.

Formation of Gel-Cured Product By curing the organopolysiloxane composition of the present invention comprising the above-mentioned components, a gel-cured product having high poisoning durability against solder flux can be formed.

In the present specification, the gel cured product is partially referred to as 3
It has a three-dimensional mesh structure and shows the state of being deformed or fluidized by stress. As a rule of thumb, a JIS rubber hardness tester with a hardness of "0" or less or ASTM D
-1403 (1/4 cone) has a penetration of 0-200.

The gel cured product is formed by injecting the addition-curable organopolysiloxane composition of the present invention into a suitable mold to cure the composition, or after coating the composition on a suitable substrate. It is carried out by a conventionally known method such as curing. The curing can be easily performed by a heat treatment at a temperature of usually 60 to 150 ° C. for about 30 to 180 minutes.

(Example) The present invention will be described in the following example. In the following examples, Me and Vi represent a methyl group and a vinyl group, respectively, and the viscosities are all values at 25 ° C. Moreover, "part" shows a weight part.

Comparative Example 1 As a molecular end group, ViMe ₂ SiO _0.5 unit 30 mol%, Me ₃ Si
Dimethyl polysiloxane containing _0.5 unit 70 mol% of O (viscosity: 800 cP) 100 parts, dimethyl polysiloxane having a terminal trimethylsilyl group (viscosity: 1000 cP) 25 parts, phenylmethyl vinyl disiloxane 0.02 part, and Me ₂ SiO unit 62 mol %, HMeSiO unit 35 mol%, Me ₃ SiO _0.5
After uniformly mixing 0.7 parts of methylhydrogenpolysiloxane (viscosity: 90 cP) consisting of 3 mol% of units, the vinylsiloxane complex after platinum chloride is added so that the platinum amount becomes 5 ppm with respect to the total amount, and the mixture is homogeneous. To prepare a composition (a).

To this composition, a flux solution diluted with toluene to a concentration of 10% was added as a flux amount of 600 ppm and mixed uniformly. This mixture was heated at 150 ° C. for 30 minutes, and the penetration of the obtained cured product was measured. Further, the penetration of a cured product obtained in the same manner without adding flux was also measured. The measurement results are shown in Table 1.

Example 1 As a molecular end group, Vi ₃ SiO _0.5 unit 5 mol%, ViMe ₂ Si
O _0.5 Unit 23 mole%, Me ₃ dimethylpolysiloxane containing SiO _0.5 units 72 mole% (viscosity: 1000 cP) 100 parts, 0.02 parts of phenyl methyl vinyl disiloxane, and, Me ₂ SiO units 32 mole%, HMeSiO unit 62 moles %, Me ₃ SiO _0.5
0.65 parts of methylhydrogenpolysiloxane (viscosity: 15 cP) consisting of 6 mol% unit was uniformly mixed, and then the vinylsiloxane complex of chloroplatinic acid was added to the total amount so that the platinum amount was 5 ppm, and the mixture was homogenized. To prepare composition (b).

A cured product of this composition was formed in the same manner as in Comparative Example 1, and the penetration was measured. The measurement results are shown in Table 1.

Example 2 As a molecular end group, Vi ₃ SiO _0.5 unit 8 mol%, ViMe ₂ Si
O _0.5 Unit 17 mole%, Me ₃ dimethylpolysiloxane containing SiO _0.5 units 75 mole% (viscosity: 1000 cP) 100 parts, and, except for using 0.8 parts of methylhydrogenpolysiloxane used in Example 1, The composition (c) was prepared in exactly the same manner as in Comparative Example 1, and the penetration of the cured product was measured. The measurement results are shown in Table 1.

Example 3 As a molecular end group, Vi ₃ SiO _0.5 unit 10 mol%, ViMe ₂ Si
100 parts of dimethylpolysiloxane containing O _0.5 unit 15 mol%, Me ₃ SiO _0.5 unit 75 mol% (viscosity: 1000 cP), and Me ₂ SiO unit 49 mol%, HMeSiO unit 39 mol%, Me ₃ SiO _0.5
A composition (d) was prepared in exactly the same manner as in Comparative Example 1 except that 0.92 part of methylhydrogenpolysiloxane (viscosity: 12 cP) consisting of 12 mol% of the unit was used. It was measured. The measurement results are shown in Table 1.

From the above results, the compositions (b) of Examples 1 to 3
The gel cured product obtained from (d) has higher resistance to poisoning by flux than the gel cured product obtained from the composition (a) of Comparative Example 1. To be understood.

(Effects of the Invention) According to the above-mentioned organopolysiloxane composition of the present invention, a gel cured product having high poisoning durability against solder flux can be obtained. Therefore, by forming this gel cured product on the surface of various electric and electronic parts, semiconductor elements, etc., its coating and sealing are effectively performed, and contamination of parts and contact failure due to hardening inhibition by solder flux are prevented. It became possible to solve effectively.

Claims (2)

[Claims] 1. When (A) an aliphatic unsaturated group is represented by R ¹ and a monovalent unsubstituted or substituted hydrocarbon group not containing an aliphatic unsaturated group is represented by R ² , 5 to 30 at the terminal of the molecule are represented. Mol% is (R ¹ ) ₃ S
iO consists of _0.5 units and 95-70 mol% of the molecular ends are R
¹ (R ² ) ₂ SiO _0.5 unit, (R ¹ ) ₂ R ² SiO _0.5 unit and (R ² ) ₃ SiO _{0.5 unit}
An organopolysiloxane having at least one unit selected from the group consisting of units, (B) an organohydrogenpolysiloxane having an average of two or more SiH groups in one molecule, (C) addition The organohydrogenpolysiloxane (B) contains a reaction catalyst, the SiH group of which is 0.5 per mole of the aliphatic unsaturated group contained in the organopolysiloxane (A).
The organopolysiloxane composition is contained in a proportion of about 3 mol. 2. A gel cured product obtained by curing the composition according to claim 1.